Vibratory telegraphy



(No Model.) 3 Sheets-Sheet 1.

S. D.v FIELD. VIBRATORY TELBGRA'PHY. No. 403,258. Patented May 14, 1889.

(No Modem a sheetssheer 2. S. D. FIELD.

VIBRATURY TBLEGRAPHY.

No. 403,258. Patented May 1'4, 1889.

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(N0 Model.) 3 Sheets-Sheet 3.

S. D. FIELD.

VIBRATORY TBLBGBAPHY.

No. 408,258. Patented May 14, 1889.

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BY d Wma n i /1 I 8 Afro/mf .5

UNITED STATES PATENT OFFICE.

STEPHEN DUDLEY FIELD, OF STOCKBRIDGE, MASSACHUSETTS.

VIBRATORY TELEGRAPHY.

SPECIFICATION forming part of Letters Patent No. 403,258, dated May 14, 1889.

Application tiled November 2 l, 1 8 88.

To @ZZ whom it may cow/cern..-

Be it known that I, STEPHEN DUDLE Y FIELD, a citizen ot the United States, residing at Stockbridge, in the county of Berkshire and State of Massachusetts, have invented certain new and useful Improvements in Yibratory rllelegraphy; and I do hereby declare the following to be a full, clear, and exact description oi the invention, such as will enable oth ers skilled in the art to which it appert-ains to make and use the same.

This invention relates to certain improvements in apparatus for the transmission of signals in accordance With What I have termed a system ot' vibratory multiplex telegraphy, wherein a constant succession of vibratory electric impulses are transmitted over a single main line and received at a distant point by means of au apparatus capable of analyzing the resultant vibrations of the transmitting apparatus and separating them into their component sets for translation by local receiving-instruments or sounders at the distant station. In my application, Serial No. 276,994, filed .I une i3, i888, I have shown both a transmitting and a receiving apparatus for use in such a system oi' telegraphy, and in the said applica-tion I .have shown a series ot' independent transmitting-keys, each oi' which, When set in operation, is intended to take up a specific rate of vibration different from the other keys and transmit the same into the main line. I have also in the said application shown an apparatus capable of analyzing and distributing the various tones to a group of tone-relays controlling a corresponding group of local sounders, by which general apparatus the resultant vibrations on the main line are received through a single coil of the general receiviiig-instrument, and by its operation are analyzed and separated into their component sets of signals and transmitted to the various local relays and thence to the Sounders.

The object of the present invention is to provide means whereby a single transmitting key in the main line may be so controlled by subsidiary keys in branch or home circuits that its movements may be so timed as to pro duce on the main line resultant vibrations, Which at a distant station in turn will pro- Scral No. 291,477. (No model.)

duce results which shall correspond to the various keys which may have been closed at the transmitting-station. By the accom pl1shment ot' such object I am enabled to dispense with all but a single transmitting-instrument and a single receiving-instru m ent in the main line, all other apparatus being included only in local circuits both at the home station and at the distant station.

For the sake of clearness I use the term key throughout the following' speciiication and claims as describing the operative assemblage of contact-points used in determining the changes of polarity from the genera tor into the main line.

My present invention comprises apparatus adapted to perform the transmission of signals under the conditions above set forth, both as to the transmitting and the receiving of the current impulses and their analyzation and local reception at the distant station, and further comprises the arrangement and combination oi devices, substantially as hereinafter more fully described and claimed.

In the accompanying drawings, which form part of this specification, Figure lis a sectional elevation and diagram of one `form of main-line transmitting-key, together With two local governingkeys for manipulation bythe sendingoperators. Fig. l is a detail of Fig. l. Fig. 2 is a diagram similarly illustrating another .torni of main-line key. Fig. 3 is a diagram illustrating a modification of the form of main-line tra]ismitting-key illustrated in Fig. 2. Fig. I is a diagram illustrating the principal features of a receiving apparatus. Fig. 5 is a modification ot the receiving apparatus. Figs. (5, 7, and S show modified forms of inharmonious vibrator for the main-line relay. Fig. 0 a diagram illustrating the variations in current-impulSes effected by keys l and 2. .Like parts are indicated by like letters of reference.

I have discovered that in. the harmonic tclegraphic system-that is, a system dependent upon vibratory current-impulses transmitted over a single line-it is not necessary to superpose one set of vibrations upon another or upon several others, but that a single set oit vibratory impulses which are the resultant effect of a number of subsidiary IOO controlled by the subsidiary local transmitting-keys-that is to say, it should be of such character that upon the closing of one of the subsidiary keys the main key will take up a certain rate of vibration, and while such subsidiary key is closed if another similar key be also closed the rate of vibration of the main key will be either accelerated or retarded, and so on through the entire series of subsidiary keys which may be in use, each one of them having its own distinctive effect upon the general result-namely, modifying the resultant rate of vibratory impulses transmitted over the main line. v

In the fulfillment of the foregoing purposes a number of different forms of the apparatus may be employed Without departing from the spirit of my invention. I will illustrate several of these in order to show the variations which may be made in transmission apparatus in accordance with my invention. One of the simplest forms isvshown in Fig. 1, which I may term a pneumatic vibrator, and I wish to say that this apparatus may be operated by the use of compressed air, steam, or any gas or liquid under pressure; but I prefer the use of compressed air on account of its being the cleanliest and involving the least complication.

13 is a reservoir, which is to be kept supplied with air under a suitable pressure,

' which may convenient-ly be fifty or seventyve pounds per square inch. This communicates by means of a pipe with the valvechamber 3. The latter is constructed with a diaphragm, 4, having the valve-ports 5, 6, and 7, to which are fitted the valves 8, 9, and 10, respectively. Each of the valves isV fitted with a stem projecting upwardly through suitable glands. Valve 8 is connected to the pivotal junction between the key-lever 11 and the lever 12, and the key-lever 1l is in turn pivoted on a bracket, 14, which. may be conveniently attached to the Valve-chamber 3. Valve 10 is connected through its stem to the pivotal junction between key-lever 15 and ,the lever 12 in a similar manner, and lever 15 is pivoted on a bracket, 1.6, also conveniently attached to the valve-chamber 3. Lever 11 at its outer end carries an armature, 17, and lever 15 at its outer end likewise carries an armature, 18. AOpposite armature 17 is a local magnet, 19, and opposite the armature 18 is a local magnet, 20. Both levers 11 and 15 are provided with retractile springs 21, as shown. Valve 9 is attached through its stem to the center of the middle lever, 12, by an adjustable slotted connectiomwhich is clearly shown in Fig. 1f.

By the foregoing construction it will be seen that if We depress the outer end of lever 1l the valve 8 willv be lifted from its seat 5.; but although that endof the lever 12 will rise correspondingly its valve 9 will not be disturbed by reason of the slotted connection.

It will likewise be seen that if we depress the outer end of lever 15 its valve 10 will belifted from its seat 7 with similar results; but if at the same instant both levers 11 and 15 are depressed at their outer ends the result will be not only to lift valves 8 and 10 from their seats 5 and 7, but the middle lever, 12, will also receive such amount of motion upwardly as to lift its valve 9 also from its seat 6 in the valve-chamber.

The operation of the levers 11, 12, and 15 `is brought about by means of the subsidiary transmitting-keys 1 and 2` acting to close their respective local circuits through the magnets 19 and 20. Upon depressing key 1 valve 8 is lifted from its seat to its full eX- tent. Upon depressing key 2 valve 10 is lifted from its seat to its full extent. Upon simultaneously depressing keys 1 and 2 all three valves, S, 9, and 10, are lifted from their seats. The lower portion of the valve-chamber 3 communicates by a pipe, 22, with the main transmittingkey,which is constructed as follows: At each end is a cylinder, 23 and 24, in each of which are tted the respective pistons 25 and 26, which are connected by the piston-rod 27.

About the centerof the rod 27, I place the piston-valve 28, which I prefer to make of aluminium on account of its lightness. Valve 2S is grooved on its periphery to form the ports 29 and 30. Surrounding the piston-valve is a casing, whose upper portion is formed with three ports, ports 31 and 32 both communicating with the pipe22, and port 33 communicating with the atmosphere. Below thevalve 28 the casing is constructed with the two ports respectively marked 34 and 35. Port 34 passes directly to the back end of cylinder 23, and port 35 correspondingly extends to the back end of cylinder 24. The piston-valve 2S ismade to'slide freely endwise on the pistonrod 27, but its movement is limited by means of the adjustable stops 36, which are adjustably fixed on the piston-rod 27.

Assuming now that the position of the parts is as shown in Fig. 1, upon closing key 1 valve 8 is lifted and a certain amount of air is allowed to rush through pipe 22, and this now passes down ports 31 and 29 into 34 and back of piston 25, immediately driving the piston to the right. In doing so the stop 36 drives the piston-valve 2S to the right and shifts the relation of the ports 29 and 30With respect to the admission and exhaust ports. In this new position, then, the ports 34 and 29 communicate with port 33 and the atmosphere, and

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port 32 now communicates with port S0, and port 35 with the rear of piston 2G, and therefore the pressure is exerted upon the last to drive it toward the left, and the piston-valve 25 is shifted accordingly. The action will be continuous so long as the pressure is admitted into pipe 22, and the speed of vibration of the rod 27 will depend upon the action of the valves S, S), and l0. The opening of valve S communicates a definite rate of movement to the rod 27. The opening of valve l0 will also communicate a definite rate; but the rate will be different, because the valve 10 is of a different arca from valve S. The opening of all three valves, 8, 9, and lO, will communicate a still different rate of vibration to the rod 27, as will be readily understood. XVe have thus provided for three different rates of vibration of the rod 27 and these three different rates are dependent upon the three conditions brought about by closing either one of the keys l or 2 by itself or by closing both of them simultaneously. The vibrating rod 27 thus becomes, in fact, the main-line transmitting-key, capable of variable rates of vibration upon the foregoing principles of operation. Its functions of transmission are performed as follows: I arrange in front of each end the respective levers 37 and 3S, having the respective contacts 39 and 40 so located as to be struck by the rod 27 as it moves. Both these levers are provided with the insulated retractile springs 4l, so as to be always drawn inwardly, and when so drawn in to close upon the stationary contacts 42 and 43. These last contacts, 42 and 4S, form one terminal of the external circuit of the shuntwound dynamo-electric machine D, to which they are both connected after passin through the resistances R, one of the latter being placed in each branch leading to the aforesaid contacts 42 and 43. The other terminal of the machine I) passes directly to the rod 27 through the frame-work of the structure in which the rod moves. Lever 37 is connected directly to the line, and lever 38 is connected directly to earth.

It will thus be seen that movement of the rod 27 to the left sends an impulse of current in one direction over the line, and movement of the rod to the right son ds a similar impulse over the line, but in an opposite direction. I prefer this method of sending alternating impulses, as it permits of greater speed of transmission than where the impulses are all in a single direction. The office of the resistances R is to prevent the generator D from losing its field-magnetism at certain times, and is commonly resorted to in the application of shunt-wound dynamos to telegraphic purposes.

The higher the speed of vibration of the rod 27 the greater will be the electro-motive force required to traverse the line-resistance and perform work at the distant station. It is therefore advisable to provide means of automatically increasing the electro-motive force in accordance with the increase of the rate of vibration of the rod 27. I accomplish this in a simple manner, as follows: In the shunt-circuit of the generator D, I place the adjustable resistances r r2, and on the keys l and 2, I place the back contacts c c2, both of which are connected by a common circuitwire to a point between the two resistances r I also place in operative connection with the keys l and 2 the rear anvils, d cl2, and these are respectively connected by separate circuit-wires to the other or outer sides of the resistances 0' r2, as shown in Fig. l. So long as the keys l and 2 are open the resistances fr r2 are both in the shunt-circuit of the dynamo D, being in series therein. The closing of either of the keys, however, acts, by means of the back contacts, to shunt out either one or the other of the resistances, and thus correspondingly increase the field-magnetism of the generator, and if both keys are simultaneously closed both the resistances r fr? are at the same instant shunted out of the fieldmagnet circuit and the magnetism is increased correspondingly, and of course in all these cases where part or all of this extra resistance is cut out the electro-motive force generated in the armature is increased accordingly.

It will therefore be evident that I may send over the line a particular set of vibrations upon closing key l, a diiferent set of vibrations upon closing key 2, and yet another distinctset of vibra-tions upon simultaneously closing both keys. The reciprocating rod 27, therefore', becomes a transmitting-key of an inharmonious or neutral vibratory character, whose periodicity of vibration may be governed to any desired extent by the application of subsidiary transmitting-keys.

One modification of the foregoing will be found in Fig. 2, wherein the main-line transmitter works by impulses of a battery passing through condensers which maybe adjustable by connecting plugs in the manner well known to the art. In this form the reciproeating rod 27 passes through the yokes of the two electro-magnets e and carries at its center the armature 44, the arrangement being such that the rod is free to move in the direction of its length. The rod 27 carries the tappets 45 and 46, which make contact with and move the levers 37 and 3S, respectively connected to the line and earth, as in Fig. l, and the direction of the current from the generator D is shifted by means of the inner contacts, 42 and 43, the same as in Fig. 1. In Fig. 2 the other terminal of the generator D passes by connection 47 to rod 27, and therefore the terminal connected with the rod 27 is thrown to line or to ground, according to the position of the rod. The respective electro-magnets e. c2 are energized by means of a battery, B, one terminal of which is branched to the two electro-magnets, so as to be capable of passing through either of them, according to the contacts made. After passing through the electro-magnets c e? the branches IOO IIO

'are carried to the respective contacts 48 and 49, each situated at the ends of the stroke of the rod 27 so that the latter will alternately close on the said contacts 48 and 49. From rod 27 a circuit is taken to the like plates of three separate condensers, C C2 C3, in multiple. From the other plates of the condensers three connections are madefrom condenser C2 a circuit to the anvil of the subsidiary key 1, from the condenser C2 to the anvil of the subsidiary key 2, and from the condenser C to an insulated contact, 50, on the key 2. The other side of the battery B is connected in vmultiple with the key 1, key 2, and with a con-r tact, 51, on key 1. Back contacts 52 and 53 are arranged to be closed upon the depression of the respective keys 1 and 2, and these back contacts are directly connected, as shown.

.The condensers will be of different capacities-as, for instance, key 1 on closing connects the battery B with the condenser C2 of la certain capacity, and will have a certain magnetizing effect on the electro-magnets e e2. Key 2 on closing connects the battery with the condenser O2, whose capacity is enough larger than C3 to materially increase the rate of vibration of the armature 44 and the rod 27. When both keys 1 and 2 are closed, the back contacts 50 52 and 51 53 are both also closed, with the result of additionally connecting the battery B with the condenser C', and the 'effect is to increase the total condenser capacity to the point necessary to accelerate the rate of vibration of armature 44 and rod 27 to the required speed. The vibration of the rod 27 is eifected by the automatic shifting of current through the electro-magnets e c2 by means of the contacts 48 and 49, as will be readily seen on following out the circuits and observing the attractive action of each of the magnets in turn upon the armature 44. A variable rate of vibration is therefore imparted to the rod 27 (which becomes the main transmitting-key) by the use of the condensers C C2 C3, instead of the pneumatic pressure explained in connection with Fig. 1, and its rate of vibration is governed entirely by the keys 1 and 2. As an instance, if the practicalarrangements are such that the closing of key 1 sets the rod 27 vibrating two hundred times per second and the closing of key 2 sets the rod vibrating three hundred times per second, then when both keys are closed the rod will vibrate six hundred times per second under the conjoint iniiuence of both keys 1 and 2, and this set of vibrations, rating at six hundred per second, will be transmitted over the line, and can there be analyzed so as to produce two independent results-at the distant station-'that is, can be separated into tended to include as many sets of vibrations as a common multiple can be obtained for,

and it will be found that this number will bear a close relation to the resistance and static capacity of the circuit upon which the apparatus is placed.

Another modification of the transmitter is illustrated in Fig. 3. This, like the apparatus shown in Fig. V2, may be termed a batterytransmitter. In this case the direction of the impulses from the generator D is controlled by an insulated tongue, 54, carried by the armature 44 on the rod 27, which is oscillated or vibrated back and forth by the alternated action of the magnets e e2, as before. The levers 37 and 38, with the contacts 42 and 43, in connection with the tongue 54, operate to alternate the direction of the impulses sent over the line by the generator. The vibration of the rod 27 is set up by closing either of the keys 1 and 2 by means of the respective pairs of back contacts 55 56 and 57 58, which close the respective circuits containing the batteries B2 B3, on the other side of which the two batteries are joined in parallel into the double branch circuit, whose two sides include, respectively, the electro-magnets e e2, continuing on then from magnet e to the contact 49, and from magnet e2 to the contact 48, the same as in the modification shown in Fig. 2.

The foregoing arrangement of keys 1 and 2, batteries B2 B2, magnets e e2, contacts 48 and 49, and rod 27, with the return-circuit 59, form together an automatic system, which, like the previously-described transmitting devices, sets up rates of vibration of the rod 27, and these rates will be variable according to the conditions previously set forth. The contacts 55 and 56 and the contacts 57 and 58v may be respectively considered in the case of Fig. 3 as the principal contacts of the keys 1 and 2; but the keys are also used for a further purpose, which will now be set forth.

Upon the shaft 27, near each end, I place the collars 60, which I prefer. to make with a V-groove in their periphery, and arranged so as to be capable of being pressed into said grooves are two pairs of L-shaped iron cores for the respective solenoids S S and S2 S2, so placed as to inductively aect the said L- shaped cores, the solenoids S S being included in a circuit containing a local battery and closed by the front contacts 61 of key 1, while solenoids S2 S2 are included in a circuit containing a local battery and closed by the front contacts 62 of key 2. The two independent contact portions of both keys 1 and 2 are insulated from each other. At a suitable point at the ends of the apparatus I fix the double vibrating forks F and F2, respectively, and these are so located that the L- shaped cores of the solenoids are pivoted to their vibrating extremities. Both forks are carried on adjustable bearings or standards H, in order that the inward extension of the L-shaped cores may be adjusted to the exact IOO IIO

position desired to prevent unequal beats in eiect is to magnetize the L-shaped cores, so that the two adjacent extremities will have opposite polarity and be attracted strongly toward each other, thus forming a species of clutch on the collars GO, and thereupon the rate of vibration of the rod 27 is brought into unison with the rate of vibration of whichever fork is at the time in engagement with the said rod by means of the L-shaped cores. In other words, upon the closing oi either one ot the keys l and 2 the rod 27 is started into vibration, and such vibration is compelled to assume a rate which will accord exactly with the fundamental of the corresponding fork. It while key l, for instance, is closed, I also close key Q, both forks F and F2 become engaged with the rod 27, and the latter is caused to vibrate at a rate corresponding to a multiple of the two rates, as hereinbetore explained, and as at this moment the magnets e e2 require to have more power than when either fork alone has been attached, I provide for this by the before-described arrangement for bringing the two batteries B2 B3 into the circuit of each of said magnets in turn in multiple, and in this arrangement I prefer to have the internal resistance of the batteries B2 B3 rather high compared with that of the electro-magnets e el. The same effect, however, may be produced in other ways, as by the use oi' continuity-preserving keys and the introduction oi' additional batteries in series in the usual manner, well known to those skilled in the art.

It is evident that manymodifications can be produced to construct a main-line transmitting-key of the general character called for by this invention, and will readily suggest themselves to one skilled in the art to which this invention appertains, whereby the sequence et vibrations proceeding from a single key may be obtained without departing from the general result hereinbefore set forth.

As an analyzing' and receiving apparatus in connection with the foregoing transmitting appliances, I prefer to use a device which I call a therinie wire receiver, whose principles have been fullyset forthin my application, Serial No. 276,994,lcd June 13,1888. Such a receiver is shown in modified form in Fig. i in operative connection with two tone-relays, T T2, and their local sounders L L2. The two relays T T2 are accurately set to vibrate at rates respectively corresponding to the rates set up in the transmitting-rod 27 by the respective keys l and 2. The main line passes through the coil G8, which is mounted on the core Gi et a tubular magnet, G5, which is p0- larized by the coil GG and local battery G7. The end of magnet 65 is closed in to form a small aperture at the center, and in this aperture I suspend a reciprocating plug ot iron, S7, by means of the thermic wire W', which is held by a snitable bracket, 68, at its upper end. Strain vis put upon the wire lV by the inharmonions spring G9, which preferably of rubber and sphericalin form, as shown, and

adjustment is aii'orded by the screw 70 in bracket 7l. Core Gi and plug 87 are iitted with the contacts 7l. A low-resistance wire, 72, leads from core (il directly to the bracket 68 and forms a shunt for the wire \V, in accordance with the principles laid down in my said application, Serial No. 276,99i. The other partof the an alyzing-circuitpasses through the magnets of the tone-relays either in multiple arc or series, and thence tothe bracket 68, including on its way the local battery B1. The line-currents excite the coil (53. As in my said application, the current-impulses set up intermittent attraction 'for the iron plug S7, which then, by making and breaking the contacts 7l, causes the local current to so affect the thermic wire as to set the tone-relays T T2 in operation, in exact accordance with the subsidiary transmitting-keys l and 2 at the sending-station- The letters n and s indicate polarity wherever placed in the figures.

A modiiication of both the analyzer itself and the local receiving-circuits is shown at Fig. 5. Here the responsive or sensitive member, instead oi being a diaphragm or a plug, is an iron or steel hollow sphere, 73, the other portions oi the instrument being as before. The repeating-circuit 'T5 includes in multiple are the magnets of three tone-relays, T T2 Ti". The circuits ot the two local sounders L L2 are in Fig. i, and, besides, a common return-wire from both sounders traverses the local circuit of relay T3. The vibrating reeds ci' the tone-relays T and T'2 are respectively tuned to correspond exactly with the rates of vibrations due to the No. l and No. 2 key at the transmitting-station, while the reed of the third tone-relay, T3, is adjusted to the vibrations due to both keys in unison. Vith this arrangement the tone-relay T will respond to the vibrations sent over the line upon key l, relay T2 will respond to the vibrations sent over the line by key 2, and relay Ts will respond to the vibrations sent over the line by the simultaneous closing of both keys l and 2, and when both said keys l and :2 are closed, should the resultant rate oi vibration not be in harmony with both relays T and T2, the third relay, T, breaks both.

Instead of the complete hollow sphere 73 as the sensitive or responsive portion of the analyzing-instrument, I may make it in the form of a hollow hemisphere, 76, as shown in Fig. 6, the remaining portions of the analyzer being as shown in the other figures. The spherical form thus given acts more in accordance with the requirements than would a flat diaphragm, as the amplitude of vibration can extend in more harmonious relation with the acting torcc-fnamely, the magnetism of the core.

In order to give the vibratory sphere or hemisphere a greater mass of iron While preserving .its mobility, I may form it with corrugations arranged in meridian lines to meet the point opposite the pole (il, as shown in IOO IIO

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Fig. 7; or I may use heavier iron or steel and divide it on meridian lines, as in Fig. 8, the pieces t' being joined at the pole by button lo, or similar fastening of elastic material, such as soft rubber. The increased mass of magnetic material thus obtained permits of a greater range of usefulness, since its saturation-point will be raised to a degree unattainable by the ordinary diaphragm, which,there fore, is more limited in respect to increase of effect with increase of vmagnetic strength; but for maximum range of magnetic effect I still prefer the magnetic plug and inharinonious spring shown in Fig. 4.

Referring again to the receiver shown in Fig. 4, it is to be noted as possessing special advantages. The primary object to be obtained is the construction of an instrument responsive to inharinonious current-impulses. The annular field and reciprocating magnetic plug enables me to have more lines of force to act upon than is possible with a thin diaphragm for armature, which quicklybecomes saturated with magnetism, and then operates only by molecular change without the bodily movement necessary for practically actuating contact-points. As the plug, however, has an appreciable amount of inertia, it should be so mounted that a balance is obtained by a spring which will automatically exactly balance the attractive force of the magnet. As the latter increases under the law of squares, the spherical form of spring compensates, because when compressed the surface increases according to the same law, and the resistance to further com pression in like manner.

l. In a system of telegraphy, the combination of a source of current, a line, and a single main-line vibratory transmitting-key comprising contacts and a controlling-vibrator therefor having a variable periodicity of vibration.

2. In a system of telegraphy, the combination of a source of current, a line, a single main-line vibratory transmittiiig-key coinprising contacts, and a controlling-vibrator therefor having a variable periodicity of vibration, and means for varying the same 0perated by subsidiary keys in local circuits.

3. lIn a system of telegraph-y, the combination of a source of current, a line, a single main-line vibratory transmitting-key comprising contacts, and a controlling-vibrator thereforhaving a variable periodicity of vibration, subsidiary keys in local circuits, and interposed controlling devices for said mainline key and dependent for Ioperation on the subsidiary keys.

4. In a system of telegraphy, the combination of a source of current, a line, a single main-line vibratory transmitting-key comprising contacts, and a controlling-vibrator therefor having a variable periodicity of vibration, and a single receiver responsive to alll the transmitted vibratory impulses.

5. In a system of telegraphy, a main-line transmitting-key comprising a vibrator having a variable periodicity of vibration, and contacts operated by saidlvibrator and controlling the direction of currents in the h ne.

6. In a system of telegraphy, a main-line transmitting-key comprising a vibrator having a variable periodicity of vibration, a source of current, and contacts arranged to reverse the current on the line at each change of phase in the vibrator.

7. In a system of telegraphy, a main-line transmitter' comprising a reciprocating rod adapted to reciprocation at variable rates of speed and having line-contacts, in combination with devices for controlling the rate of speed, subsidiarymanipulating or make-andbreak keys in local circuits,land magnets 1n the local circuits operating said controlling devices.

8. In a system of telegraphy, a main-line transmitter comprising a reciprocating device arranged in operative relation to the line-contacts and capable of variations in its lrate of vibration, a source of energy for effecting the movement of the reciprocating device, and a group of subsidiary make-and-break.keys controlling the amounts of energy applied to the reciprocating device.

9. In a system of multiplex telegraphy wherein the signals are made by makes and breaks in sets of vibrations of different rates, a source of current, a vibratory transmittingkey capable of varying rates .of vibrations, and a group of subsidiary manipulating-keys controlling thevibration of said transmittingkey, and having eXtra contacts arranged 1n operative connection with the source of cui'- rent and automatically governing its electromotive force.

IO. In a system of multiplex telegraphy wherein the signals are made by makes and breaks in sets of vibrations of different rates,

vthe combination of a single source of current,

an inharinonious vibratory transmitting-key, and a group of subsidiary manipulating-keys controlling the vibration of said transmittingkey, each subsidiary key having extra contacts arranged in local circuits con trolling the source of current of the main line and in operative connection with the source of energy of the transmitting-key, whereby the potential of the current source is raised with increase of vibratory rate and the motive power of the transmitter is increased correspondingly. n

ll. In a system of telegraphy, a main-line transmitter comprising a neutral or inharmonious vibratory key, in combination with a tuned fork adapted to be placed in controlling connection'with said key, whereby the latter is forced to vibrate in unison with the fork.

12. In a system of telegraphy, a main-line transmitter comprising a neutral or inharinonious vibratory key, in combination with two or more timed forks adapted to be severally or jointly placed in controlling connection with said key, whereby the latter is forced to IOO IIO

vibrate in unison with any one fork separately connected to it, and vin unison with a multiple of the several rates of Vibration when more than one tori; is connected to it.

i3. In a system of telegraphy, a main-line key comprising` a pair of pistons connected by a rod and having suitable line-contacts and a valve and ports for effecting the reciprocation of the rod, in combination with a source ot' pressure and interposed admission valves controlled by subsidiary keys in respectively independent local circuits, each including electro-magnetic devices for operating` one of the said admission-Valves.

14. In a system of teiegraphy, a receivinginstrument comprising a magnet, a magnetic plug adapted to reciprocate in the iield of the magnet7 and an nliarmonious com pensating` spring` opposing the attractive force of the magnet.

l5. In a system of telegraphy, a receivinginstruinent comprising a magnet, a magnetic ping adapted to reciprocate in the field of the magnet, and an inharmonious spring of spherical form Whose resistance under compression SHEPHEN DUDLEY FIELD.

Witnesses:

T. J. MGTIGHE, EMILE IIENKEL. 

